1. Field of the Invention
The invention relates to a method and to a device for data processing in a mobile communication network and to a system comprising such a device.
2. Description of Related Art
3GPP defines in release 8 (Rel.8) an architecture for the packet core. A System Architecture Evolution (SAE) describes how a packet core network can be extended to integrate non 3G accesses into the system architecture. FIG. 1 shows interfaces and components of a non roaming architecture for the evolved packet core network according to specification 3GPP TS 23.402 V8.2.0, entitled “Architecture enhancements for non-3GPP accesses”.
The specification of the evolved packet core describes how the specific characteristics of heterogeneous access networks can be hidden from a mobile user. Access network convergence implies a similar “look and feel” experience for the application regardless of the type of access that is currently used by a (mobile) device.
Service continuity among those heterogeneous access networks is one of the prominent features, which is expected to increase the popularity of Rel.8 as well as upcoming versions. Also, service continuity may speed up a deployment of associated or required network components.
A PDN-GW represents a gateway node for the packet core towards an external network. It may also comprise an anchor function for trusted and/or un-trusted non 3G access networks with the support of a network based mobility protocol PMIP (Proxy Mobile IP according to IETF RFC 5213, entitled “Proxy Mobile IPv6Client based MIPv6”) (see interfaces S2a and S2b in FIG. 1).
For an un-trusted access, a VPN tunnel can be used with an evolved Packet Data Gateway (ePDG) representing a tunnel endpoint on the core network side. Mobility support by the user equipment (UE) is also addressed by IETF RFC 3775, entitled “Mobility Support in IPv6”. The respective interface S2a (not shown in FIG. 1) is also terminated in the PDN-GW regarding the non roaming case.
Even though handover between heterogeneous accesses has been specified as part of SAE, there are problems regarding a handover procedure due to unsynchronized events. It is further not defined as how to react to changed conditions in the new network. Hence, the UE does not know when to switch between a non 3G access network and a 3G access network. As not all end devices may be able to maintain simultaneous IP connectivity among several interfaces, a UE may have to switch IP connectivity between the non 3G interface and the 3G interface. If the UE switches such connectivity too early, packets received on the non 3G access could be lost. On the other hand, if such switching is conducted too early, packets may have already been delivered via the 3G access without the required connectivity being established. As a result, packets get lost.
In addition it is not apparent to the UE for the handover from the non 3G access to the 3G access whether the reservation was successful and how many resources could be reserved per data flow to be transferred.
The problem to be solved is to overcome the disadvantages stated above and in particular to provide an efficient approach to synchronize handover between a 3G access network and a non 3G access network.